So far, for example, Patent Literature 1 discloses a control apparatus for an internal combustion engine that includes an in-cylinder pressure sensor. Since detection values of the in-cylinder pressure sensor are gauge pressure relative to atmosphere pressure, it is generally required to perform absolute pressure correction. Accordingly, the aforementioned conventional control apparatus utilizes Poisson's equation to calculate an absolute pressure correction value based on in-cylinder pressure and in-cylinder volume at each of two crank angles in the adiabatic compression stroke from the closing timing of an intake valve to a spark timing and the ratio of specific heat (that is to say, based on a parameter PVκ).
Including the above described literature, the applicant is aware of the following literature as related art of the present invention.